I posted this to the use-list, but maybe this is a more appropriate venue:

The new LC8 IDE implements the publish-and-subscribe pattern,
but it looks like it isn't designed to be extensible. It's extensible
right now because revIDEMessageIsValid() always returns true.

Q: assuming that the validity check was an interim test to make sure
the IDE didn't fall on its face, can we rely on this mechanism as a way
to register callback events in the IDE, and thus extend and modify
the IDE?